22 August 2016: What do urban agriculture, the dark sky movement, and low-impact storm water management have in common in the United States? Very often these sustainable development practices involve the decommissioning of public infrastructure. And the impetus to implement these techniques often has more to do with saving money than saving the environment.

Many American cities with shrinking populations have chosen to enter the 21st century by recreating 19th century landscapes. Decaying industrial and residential neighborhoods in cities like Detroit and Cleveland have been replaced by hectares of agricultural land. Crop fields, hoop houses, animal barns, and, in Buffalo, New York, a fish farm stand where vacant homes and businesses were demolished. Municipal contraction through major decommissioning of infrastructure is viewed as responsible land use policy by many urban mayors. Former Youngstown, Ohio Mayor Jay Williams, who is credited with starting the debate on “rightsizing” shrinking American cities, unequivocally calls it “progress”, reminding people that ”a smaller community doesn't mean an inferior community.”

Other cities are switching off street lights to save money. Colorado Springs, Colorado turned off over 8,000 of its least energy efficient street lights, saving $1.2 million annually. When skies are darker, stars are more visible, energy is saved, and city budgets are relieved. Cities have also begun to unpave asphalt roads in response to budget pressures in at least 27 US states, according to the National Highway Cooperative Highway Research Program. The NHCRP notes that almost all of the unpaving of roads in the US occurred in the past five years. Advocates say that unpavingreplacing macadam with gravelsaves money and provides a permeable surface for storm water to percolate into the ground.

The trend of managing public assets by decommissioning infrastructure is followed by cities of all sizes in the US. There have been notable successes. The High Line in New York City, a railway that was unused for 20 years and thoughtfully transformed into a pedestrian thoroughfare, is an international model of re-purposing decrepit infrastructure. Similarly, the small city of Corning, New York turned the motor vehicle lanes of its structurally-deficient Centerway Arch Bridge into a landscaped pedestrian walkway over the Chemung River.

Most often, however, mayoral policies to decommission public infrastructure aren’t based on empirical evidence of its effectiveness. “We can’t wait to get things done,” said former Detroit Mayor Dave Bing in announcing his city’s ambitious plan to demolish tens of thousands of vacant buildings and replace them with farmland, open space, trails, and parks. The urgency of mayors and other government officials to reduce or eliminate infrastructure as a way of balancing falling municipal revenues with rising municipal expenses has outpaced efforts of urban planners and engineers to devise technical and ethical standards for reducing public facilities.

Sound technical and practical criteriaWhat are some of the technical and practical considerations, which a small but growing number of studies suggest are important for decommissioning public infrastructure?

Redundancy is a key issue. The American cities that are challenged to manage infrastructure with fewer funds and a lower population base are often older cities with streets laid out in a grid pattern. In urban areas, the grid allows not only a walkable community but also redundancy for access to properties, for continuing services during infrastructure maintenance shutdowns, and for fire protection and other emergency situations which place a high demand on infrastructure. While the grid layout provides convenience and safety, it makes it difficult to remove components of utilities such as water and sewer. Rather than eliminating the benefits of redundancy, cities may find it wiser to reduce costs through shared administration and reduced energy costs.

In general, recent studies find that the decommissioning of water, sewer, and gas lines, and water and wastewater treatment plants in urban areas is difficult to justify technically. It is often preferable to incur the costs of maintaining these assets, even at a minimal level, rather than remove a service that may be needed in the future. Excess infrastructure capacity can also be a competitive advantage in attracting economic development.

The primary road systems of many rural cities were also laid out in grid patterns. A one-mile grid made it easier for horse-drawn carriages to get around in a reasonable amount of time. Today, it takes only minutes to travel the extra mile, and many rural cities have more bridges than they need. In the past ten years, hundreds of redundant bridges have been closed in rural USA, saving cities millions of dollars on maintenance and replacement costs. Many larger urban cities also have an excess number of bridges, as many as three in a one-mile stretch, that once were needed for the high volumes traffic associated with a long-gone manufacturing industry and a much larger population base than now exists. Adaptive reuse often works better than demolition, and many bridges which are no longer needed for personal vehicles have been turned into pedestrian trails, tramways, and other amenities.

The true decommissioning of roads is rare in the US because roads provide access to homes and businesses. The need for access still exists even when the level of usage declines. It is becoming more common for roads to be “downgraded.” For example, rather than repave rural roads originally designed for light traffic that were severely damaged by heavy trucks carrying oil and natural gas during the current energy boom, the state of Texas decided to remove the torn-up asphalt and replace it with gravel. Maintenance costs are considerably lower for gravel roads; however, there are no national standards for unpaved roads as there are for paved roads in the US. Critics note that rainwater runs off unpaved roads like paved roads, thus eliminating the perceived benefits of a gravel road surface for storm water management. Moreover, unpaved roads are prone to erosion.

Turning off or turning down street lighting is perhaps the most prevalent means of decommissioning infrastructure used by American cities. Santa Rosa, California, for example, removed 6,000 streetlights and put another 3,000 on timers to save about $400,000 annually. The Department of Transportation of the state of New Hampshire shut off non-essential lights on state-maintained roads in cities throughout the state due to budget cuts. Several cities have adopted dark sky policies to protect the night skies from light pollution in conjunction with extinguishing street lights.

While cities inevitably look at cost-saving measures first, other standards are important, such as: maintaining intersection lighting in residentially-used areas but considering decommissioning or part-night lights in other residentially-used areas; decommissioning lights on non-residential streets without sidewalks, bridge areas, industrial parks, and rural areas of low use; replacing inefficient units across the street lighting system; and implementing dimming and part night lighting. Turning off or dimming lights requires close collaboration between the public works and police departments to develop a list of lights that can feasibly be turned off. Lights should remain on at schools, intersections, low speed curves, and high accident locations.

Lorain, Ohio, like other cities, removed not only street lights but also traffic lights. The traffic lights were replaced with stop signs. The city’s drop in population meant fewer vehicles on the road and the need for fewer traffic lights to control them. Removing signals and replacing them with stop signs can save money as long as a traffic analysis determines that traffic conditions, pedestrian safety, intersection geometry, and physical characteristics such as school zones and sight distances warrant the downgrade.

EthicsTaxpayer money, public safety, and economic growth are not the only concerns about decommissioning infrastructure. The wholesale decommissioning of city neighborhoods may involve relocating residents. While most of the residents of a decaying urban area targeted to become green space or agricultural land may relocate voluntarily, some property owners may be forced by the city to move, and the expropriation of their land and buildings extinguishes private property rights. Many individual owners in a decaying neighborhood will receive fair compensation for their properties - probably the only fair compensation they could ever hope to receive - and a chance to relocate to a more desirable part of the city. However, there are few follow-up studies of relocated residents to study the effects of moving on their lives and life prospects. There is even scanter evidence that decommissioning infrastructure, demolishing vacant properties, and installing new green space and agriculture fields, will “create value in the habitable properties that remain, and attract investors and residents back to these neighborhoods devastated by decay,” as asserts Buffalo Mayor Byron Brown in his Rightsizing Buffalo report.

More broadly, decommissioning public infrastructure at any level reduces the scope of the local government and thus resonates with advocates of smaller government. However, clear standards are needed to ensure that smaller local government is fair to all residents and property owners.

Opportunities and concernsDecommissioning public infrastructure thus presents opportunities and legitimate concerns. In some cases, the cost savings are clear; in others, the maintenance cost savings don’t justify dismantling a facility that may be useful in the future. The pressure to save money can also be a catalyst for a city to become more energy efficient and environmentally conscious.

Although widespread decommissioning in a recent phenomenon in the US, it seems clear that successful and equitable implementation requires a systematic approach to support a non-arbitrary, consistent decision making process. Public input is also needed as residents will have strong opinions one way or the other.

In June 2016, 200 mayors from the US Conference of Mayors issued a resolution asking the federal government to give municipalities more money to upgrade their crumbling infrastructure. That same month, Baltimore mayor Stephanie Rawlings-Blake announced a program to demolish about 4,000 vacant structures in her city. Without more money to modernize public facilities, the pace of demolition, rightsizing, and decommissioning can be expected to quicken in US cities. Decommissioning “is the last resort, not the first,” says Baltimore Housing Commissioner Paul Graziano. “It has to be strategic.”